Spectrometric instruments include a light source, a test sample, a dispersion element such as a diffraction grating, a detector that may be a linear array of diode receptors (pixels), and appropriate connecting optics. Modern instruments include a computer that receives spectral signals from the detector to process the signals. In one type of instrument, the light is passed through the sample so that a transmitted beam is detected. One type of light source is a flash lamp, and the sample may be dissolved or suspended in a cuvette of carrier liquid.
With improvements in optics, detectors and computerization, there has evolved an ability to perform very precise measurements. However this has resulted in fairly expensive instruments and complex operations. There is a need for both lower cost instruments and simplicity of operation, particularly with sufficient automation for an operator to do little more than select type of sample, insert the sample and start the instrument. In the case of a sample in a carrier, an added step for a blank (carrier without sample) may be desired. Such instruments are desirable currently in molecular biology such as for determining concentrations of proteins and nucleic acids including RNA and DNA.
Lower cost components are subject to fluctuations in performance between instruments and drift in each instrument. Therefore, the automation should provide for frequently checking and resetting operating point associated with the flash lamp and detector readouts, further resetting for narrower spectral range if automatically selected for a sample type, correcting for stray light and non-linearity, and wavelength calibration.
An object of the invention is to provide an improved spectrometric instrument having relatively low cost and simplicity of operation. Another object is to provide such an instrument with means for automatically checking and resetting operating point to optimize performance, repeatability and drift correction. A further object is to provide such an instrument with means for resetting operating point for narrower spectral range. Other objects are to provide such an instrument with means to correct for stray light and non-linearity, and to calibrate for wavelength. An additional object is to provide such an instrument with means for calculation of auxiliary information associated with the sample and derived from input of auxiliary data through a touch screen.